I have a Bitx40v3 that hasnt been getting much use since I got my ubitx.? I have been thinking about using it for digital modes, but before I do, I need to get firmware on it that will support CAT control.

The ideal situation would be if there was firmware to be found that supported CAT on the USB interface the same way as Ian Lee's CEC firmware for the ubitx.? I have poked around and read through a few of the versions on github and havent found it, so....is there a version of Bitx40v3 firmware out there that supports CAT on the USB interface?

I am a programmer, so I COULD hack together something of a mashup of the bitx40 and ubitx (cec) if it came to it, but looking to see if someone has already done so

Thanks!

Sean

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Warren & All,

Unfortunately the findings of Alison and others are dispersed over many different titled discussions.
The topic of spurs / spur reduction has being raised just in the last couple of months in threads:-
Understanding Spurious Emissions
si5351a CLK drive levels in uBITX #ubitx
Spurs for Dummies? #ubitx-help


I've highlighted mainly the gain flattering threads for my own attention.? [BITX20] RF power chain mods and improvements..? /g/BITX20/message/54483
but the thread extends many posts before & after.....

Personally I'm a confused, dumb bystander. trying to get my head around:-
/g/BITX20/message/53210
and
/g/BITX20/message/52826?
/g/BITX20/message/51802
/g/BITX20/message/51645
that need clarification?

There is a statement that Spurs are not an issue below 20mhz as the filters work for that range.
The problem is trying to operate on 15,12 or 10M at any power level on SSB.
CW TX is not an issue due to the way the radio operates, the Si5351 does CW transmit. This is fairly unique and provides a clean CW transmit.

We now acknowledge at-least some units have issues with excessive spurs when tested on CW on 80Mtrs?

To the experts
Is the general spur issue likely to affect most units, or is it an unfortunate result of component tolerances combining the 'wrong way' and can be dialled out by attention to bias / signal levels??
I used to think it was salvageable with experimentation on my part retaining it as a multiband design, but with the fresh findings.....
It's a shame the uBix is like effected, as the TX spur problems are what prevented the Minima & HF1 designs making prime time?

Alan

I always use external low pass filters I have done some years ago. They are six according to the frequencies and can be put in series to increase harmonics attenuation. No relays, just plug and play. I know it is a rudimentary solution but I think it solves many issues in homemade stuff.

Jerry,

if you move the keying to the either of the earlier mixers CW becomes a victim of
the Spur issue.

As to the corner frequency the offending harmonics are 2nd, for 3.5 its 7mhz above the 80m filter
and the third which is particularly strong at 10.5mhz well above the 80m filter.? I did sweep mine
and it was not at all bad for a 7 element filter.? However relay blow by does not help.

FYI the EBY filter was revised to improve it but its still a low pass filter.? However if it were between
the first mixer and the power amp it would help greatly up to 20mhz.

When I look back at Warren's SA out put it shows the harmonics I was seeing while testing for improved
flatness whenever I over drove the amp.? Which is why I asked if he tried lowering the drive to see
if the harmonics drop faster than the power.? ?The unmodified amp has a strong tenancy to run out
of power ( current or voltage limiting) in the predrivier and driver stages even at the low end of the
range.? That sweep goes to 30mhz so there are a lot of higher order harmonics and spur products
visible.? ?Even when your seeing 10W at 80M? its hitting the wall at 10.5mhz (third harmonic)
as well as the higher harmonics.

A reminder for those working with linear amps the power out is the total of all the amplified signals
including those stopped by filters.? There are a lot of milliwatts in those harmonics even if they never
get past filters they still help heat the drivers and finals.


Allison

Correction -- My unit is not illegal on all bands. Spectrum Analyzer output for each band can be found in the Photos section at?/g/BITX20/album?id=65861. Here is the summary:

80 meters - SSB: OK? ?CW: No
60 meters - SSB: No? ?CW: No
40 meters - SSB: No? ?CW: No
30 meters - SSB: No? ?CW: No
20 meters - SSB: OK? ?CW: No
17 meters - SSB: OK? ?CW: OK
15 meters - SSB: OK? ?CW: OK
12 meters - SSB: OK? ?CW: OK
10 meters - SSB: OK? ?CW: OK

These measurements are for a sample of one. All measurements were made at 2 watts for consistency and to avoid any overload or clipping issues. This does not mean YOUR unit is illegal! I have no way of knowing how consistent this problem is...... I suspect it is the same with all units but it is your responsibility to operate legally and there is good reason to believe if you are using one of the "No" modes above, you might be missing that bar.

WA8TOD

Warren,

Not for harmonics.? The spur issue took precedence.
They were shared in other message threads here.

The spur issue was discovered during power amp improvements.
IT was announced here in the forum and also on the ubitx.net site.

IT was why I suggests keying the modulator as then CW cleans up
leaving only the above 20mhz spurs.??

Basically for any band above 20mhz there are spurs below the cutoff of the 10M filter.
Specific example is at 28mhz the spur is 17mhz (+- offsets).? At 21mhz the spurs
are 24mhz (they move up as you move down).? At 14mhz the 20M filter catches any
spurs but not the 30mhz filter.

That is why I said band pass filter before the transmitter would clean up a lot of issues.
Those being harmonics, spurs and some of the oddball mix products visible.

From my point of view my radio is not going to see an antenna other than as RX.
I am looking at how i can make it suitable for use as transceiver.?

Its up to others on this to evaluate the data made available and use or not use.

Allison

This picture shows the 2 way pins can be soldered reverse on the nano, i choose the first one (not on the desktop) leaving plastic on the CH340 side, it allow using the nano either normal or reverse side (if you don't leave the plastic this side you cannot use Nano on the normal side), BUT you have to take care to do nice soldering with metal getting inside the holes.

Hello,

This email message is a notification to let you know that a file has been uploaded to the Files area of the [email protected] group.

File: ubitx_cat.ino_modified_KD8CEC_F1MQJ.txt

Uploaded By: f1mqj

Description:
Modified file for v4.3 original firmware (published on may 23) to include communication with KD8CEC memory manager (very usefull for getting/init settings -calibration/BFO). Only lines between KD8CEC F1MQJ comments are modified (0xDB and 0xDC CAT commands). Modifications are the same than described in KD8CEC http://www.hamskey.com/2018/01/how-to-use-ubitx-manager-for-original.html but adapted to V4.3 original firmware. (remove all text after .ino in your firmware directory -replacing original ubitx_cat.ino). tnx to KD8CEC Hope this can help - Remi - F1MQJ Use at your own responsability

You can access this file at the URL:
/g/BITX20/files/ubitx_cat.ino_modified_KD8CEC_F1MQJ.txt

Cheers,
The Groups.io Team

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Ian,
Thanks, I think the usb lead out the back is the plan.? Didn't get the pot pic.? Or haven't found it yet.? Yes, the shaft on Sunil's pot is too small for the knob.? Did you remove his power switch or parallel the two switches?
ee at eddieesserman dot com will work coming this way.? list server doesn't take to email addresses.
Eddie

Ian,

the list server deletes emails.? What is your domain after the @ xxxxx.yyy

Thanks.

Eddie

My unit puts out illegal harmonics on SSB on all bands below 20 meters.

WA8TOD

Thanks, Ian.? Got it.?

Eddie

Terry,

You need a separate band pass filter for each band if you want to use the single conversion BitX40. The UbitX uses double conversion that eliminates that requirement. You could use a multiple band pass filter, (QRP Labs has them) but then the cost is getting closer to a UbitX once you do that.?

A search within yahoo groups and groups.io for "antennas" finds dozens of such groups.
Also also some in the www.arrl.org forum, and forums.qrz.com forums, among others.
Some with one or two members.
This one has over 4311 members:
? ??

Once this new group has more than a few thousand members I might consider hanging out there.
Though it might be a good place to move discussions in this forum that veer off topic.
Like this discussion.

Jerry, KE7ER

Mike,

You solved the source issue....

with the counterpoise as suggested I did say the SWR will likely change.
Generally the 1:9 scheme is problematic for RF in the shack unless you have
luck or resort to choking...

You might try a End fed half wave as when the wire is tuned you will have less RF.
Also if the bands of interest are the 40/20 there are a few that do them well.
Though a town home is likely a noisy are a for 80/75M.??

However that picture scares me...? ;)

Allison

This is primarily an SSB transceiver, and harmonic suppression seems adequate in
that mode on the stock rig.? Best and easiest fix is probably to either not use CW mode,
or do a minor hack to move the CW mixer injection an earlier mixer so the 45mhz
filter takes out the harmonics?as previously stated.
?
The uBitx relay arrangement is not that uncommon, though would be better
to double the relay count and use separate relays for input and output.
Board layout is important.? This guy definitely knows what he is doing:
? ??

Another solution might be to get an outboard set of filters such as the WA2EBY fllter board:
? ??

LPF's such as seen on the uBitx are usually adequate for use with class C amps
on CW transmitters (which are dealing with high power square waves).??
However the uBitx gets by with as few LPF's as possible by covering multiple
bands with each filter.? The corner frequency of the LPF may be a bit high to?
fully suppress the harmonics of the lowest band of that set.

Jerry, KE7ER

Iz oos,

TLTs can be made with low loss.? ? However making a matched set may be harder
as they have to have the exact same phase response.

Also the 1:9 is 450 ohms? (50*9).

Allison